This invention relates to a battery cell and a method for producing the same.
A battery cell typically includes a separator material sandwiched between two oppositely-charged electrodes. The oppositely-charged electrodes are generically referred to as an electrode and a counter electrode. The term electrode identifies either a positive (cathodic) electrode or a negative (anodic) electrode and the term counter electrode identifies the other electrode.
A battery bi-cell typically includes at least three electrodes layered in an electrode/counter electrode/electrode or counter electrode/electrode/counter electrode relationship. Separator material can be included in the electrode and/or counter electrode of the bi-cell.
Polymer film batteries are commonly constructed from one or more cells or bi-cells. The bi-cells are normally arranged in a stack and enclosed in a battery package. A positive terminal strip and negative terminal strip extend outward from the package. Each bi-cell typically includes at least one electrode tab and at least one counter electrode tab connecting the bi-cell to each respective battery terminal strip. In this manner, the electrode and counter electrode tabs provide a circuit for charging and discharging the battery. In most applications, it is desirable to encase the battery in the smallest possible package. As a result, gathering the electrode and counter electrode tabs from each bi-cell and routing such tabs to the respective battery terminal strips within a small battery package presents difficulties.
Conventional electrode tab designs used in parallel plate cell constructions have several shortcomings. Such tab designs produce a bi-cell having loose internal component tolerances, inefficient volumetric utilization of the battery package geometry, and a fragile mechanical structure.
Further, conventional bi-cell manufacturing methods also have several shortcomings. Such bi-cell fabrication methods are complex, wasteful of material, and require a large number of tolerancing and alignment steps. Accordingly, it would be desirable to provide a cell design and method of producing the same which overcome the shortcomings of the prior art.
The present invention provides a battery cell including an electrode having an area defined by a perimeter including an edge, a counter electrode having an area defined by a perimeter including an edge, and a separator having an area defined by a perimeter including an edge. The separator is sandwiched between the electrode and the counter electrode in a layered relationship with at least portions of the edges being contiguous. The separator and one of the electrode and the counter electrode each include a first notch in the edge exposing a portion of the other of the electrode and counter electrode.
The separator and the other of the electrode and the counter electrode each include a second notch in the edge exposing a portion of the one of the electrode and the counter electrode.
A method of producing a battery cell in accordance with the present invention is also provided. The cell includes a plurality of film layers, a plurality of current collector layers, and at least one separator layer. Each current collector layer includes a predetermined lead portion. The method includes the steps of: providing at least one notch in each layer, and stacking the layers with the notches arranged with one another to expose the predetermined lead portion of each current collector layer.